block: Unhash also block device inode for the whole device

Iteration over partitions in del_gendisk() omits part0. Add
bdev_unhash_inode() call for the whole device. Otherwise if the device
number gets reused, bdev inode will be still associated with the old
(stale) bdi.

Change-Id: I7aabb82a791e19f6a5c5fa6ad21c5cdfa58bd5c4
Tested-by: Lekshmi Pillai <lekshmicpillai@in.ibm.com>
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Jens Axboe <axboe@fb.com>
Git-commit: d06e05c026ab58121dc6ab37c11f855ff642531e
Git-repo: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable.git
[riteshh@codeaurora.org: Resolved merge conflicts]
Signed-off-by: Ritesh Harjani <riteshh@codeaurora.org>
diff --git a/block/genhd.c b/block/genhd.c
index 183255c..e299597 100644
--- a/block/genhd.c
+++ b/block/genhd.c
@@ -655,6 +655,7 @@
 	disk_part_iter_exit(&piter);
 
 	invalidate_partition(disk, 0);
+	bdev_unhash_inode(disk_devt(disk));
 	set_capacity(disk, 0);
 	disk->flags &= ~GENHD_FL_UP;